Mounting for piezoelectric crystals



Dec. 28, 1948. F.. GRAY 2,457,145

MOUNTING FOR PIEZOELECTRIC CRYSTALS Filed Jan.L s, 194e Patented Dec.28,v 1948 MOUNTING FOR PIEZOELECTRIC CRYSTALS Frank Gray, London,England, assignor, by mesne assignments, to International StandardElectric Corporation, New York, N. Y., a corporation of DelawareApplication January 45, 1946, Serial No. 639,291 In Great BritainJanuary 23, 1945 (Cl. P11-327) 4 Claims. 1

This invention relates to mountings for piezoelectric crystals; and hasfor its object to provide a mounting that is of simple manufacture whileensuring a secure grip upon the crystal and attaining the correctelectrical conditions.

The main features of the invention are set out severally as claims l to4 of the statement of claim that ends this specication.

The invention will be described with reference to the accompanyingdrawing, in which:

Fig. 1 is a front view of a crystal holder assembly in accordance withthe present invention, the cover being sectioned in order to expose theelements.

Fig. 2 is a plan view thereof, the cover again being sectioned for thepurpose stated; and

Fig. 3, 4 and 5 are front view, side view and plan view respectively, onan enlarged scale, of the contact and supportingspring which appears inthe earlier figures as the means carrying the crystal.

As shown in Figs. 1 and 2 of the drawing, a base-plate I of insulatingmaterial has a closetting cover 2 also of insulating material. Withinthe chamber defined by this base-plate I and cover 2, and mounted on thebase-plate, is a quartz crystal 3. This crystal 3 consists of a squarelamina 4 with electrode coatings 5 on the central portions of its mainfaces. The electrode coatings 5 are in electrical connection withrespective terminals 6 in the form of plug-pins projecting from theunder-side of the base-plate l. The present invention is concerned withthe mounting of the crystal and the connection of its electrodes to theterminals.

The quartz crystal 3 is gripped cornerwise between the two springbrackets 1 of which one is shown on an enlarged scale in Figs. 3, 4 and5. The spring brackets 1 are of L-shape with a fixing limb 8 and anupstanding limb 9, The ilxing limb 8 lies flat on the top of thebase-plate I against which it is clamped by means of a nut II! screwedonto the threaded shank I I which passes through a hole I2 in the xinglimb 8 and which is integral with the plug-pin 6 forming the terminal. Ashake-proof washer I3 underlies the nut I0, and a rectangular stud I4 onthe base-plate I fits into a corresponding rectangular recess I in thefixing limb 8 so that the spring bracket cannot turn about the shank II. The two brackets 1 when in place hav-e their upstanding limbs 9 inparallel at a distance apart appropriate to the dimensions of thecrystal 3.

Each of the upright limbs 9 is formed near its top end with a V-shapedrecess I6, the angle of the V being rather less than say 85. Into theseopposed recesses t the diagonally opposite corners of the square lamina3 of quartz crystal, a gripping pressure being exerted both along thediagonal between the two brackets and also across each corner by reasonof the acuteangle of the V. In consequence, the crystal is rmly heldagainst movement in any direction within the plane of the crystal, butthe springs are made of a material thin and springy enough to allow thecrystal to oscillate to any frequency.

Each bracket 1 is also formed with two Wings'trips I1 .which extend upon either side of the upright limb 9 parallel but at right anglesthereto, being integrally connected with the upright limb 9 at thelowerends and having their free upper ends on a level with the recess I6. Thewings are bent inwards towards one another, and near their free-ends areformed with inward projections I: thus the two co-operating wings exerta gripping pressure depth-wise upon the quartz lamina 4 across itscorner.

Each of the central electrode coatings 5 on the quartz crystal has twoextensions I9 to adjacent corners of the lamina 4, so that however thecrystal is inserted into its holder, still the two electrode coatingswill make electrical connection, one with a wing I1 on one bracket 1 andthe other with a wing on the other bracket. However, to make quite sureof the electrical connections, wires 20 are taken from the brackets 1 tothe appropriate one of the extensions I9 at the top and bottom of' thecrystal, being soldered at their ends.

What is claimed is:

1. A mounting for a piezo-electric crystal in the form of a squarelamina comprising two spring strips mounted parallel to one another andeach having a free end provided with a V-shaped recess, said recessesbeing adjacent and facing one another, said recesses being shaped sothat said V has an angle slightly less than one right angle forreceiving opposite corners of the crystal and for exerting a grippingpressure transverse to the diagonal between said corners.

2. A mounting for a piezo-electric crystal a-ccording to claim l furthercomprising two pairsl of wings, one pair being mounted on each of saidstrips, the wings of each pair being arranged to grip the crystaldepthwise at the said opposite corners.

3. A mounting as claimed in claim 1 in which the electrical connectionsto electrode coatings on the faces of the crystal are made through saidspring-strips.

2,457,145 3 '4 4. A mounting as -claimecl n claim 1 in which the springstrips are in the form of bracket mem- UNITED STATES PATENTS bers fixedupon a base-plate by nuts threaded Number Name Date upon bolts which areintegral with terminals on 1,965,591 Gebhard July 10, 1934 the undersideof the base-plate. 5 2,329,497 Washburn Sept. 14, 19413 FRANK GRAY.2,392,429 Sykes Jan. a, 1946 2,409,838 Cress Oct. 22, 1946 REFERENCESCITED FOREIGN PATENTS mber Country'v Date Nu 10 VThe followingreferences are of record in the 508,657 Great Britain u July 4, 1939file of this patent:

